347 or 402 ?
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Instructor
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From: Lubbock Texas
347 or 402 ?
I am sure this question has been asked before but here it is. I currently have an A@A P1 kit on a stock Ls1, I am planning on going forged soon and not sure whether to go 402 or 347. First, is the P1 enough blower for a 402, I only want 8-10 pounds of boost. Second, I have an auto trans with a 3000 converter, will I really notice the added low end and midrange power from a 402 with this setup. Car puts 502hp to the wheels now, I only want to add another 50 to 100hp and make it reliable. Thanks.
Life Time NCM #2196
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From: Converse TX
Originally Posted by Devildog5150
I am sure this question has been asked before but here it is. I currently have an A@A P1 kit on a stock Ls1, I am planning on going forged soon and not sure whether to go 402 or 347. First, is the P1 enough blower for a 402, I only want 8-10 pounds of boost. Second, I have an auto trans with a 3000 converter, will I really notice the added low end and midrange power from a 402 with this setup. Car puts 502hp to the wheels now, I only want to add another 50 to 100hp and make it reliable. Thanks.
Race Director
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From: ECS : WTF did you break now and HTF did you break it this time
I have a turbo car, but honestly the car makes enough power based on boost vs. cubic inches......I wanted a 402.....ecs talked me into a forged 346 for a hell of alot less, 710/640 is more than you can get to the ground most of the time.....bigger engines are nice but more necessary NA than FI
Safety Car
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From: Hayward California
Big cubes are a nice complement to centrifugals. May need to go smaller on the pulley but it'll make for a nice power curve.
Having said that, if it were me personally, I'd run what's current, go w/ alky, a smaller pulley and retune. Run it till it dies and then go 402. IMO, It just doesn't make sense to me to put 6k in and get 50-100hp out.
Arnel
Having said that, if it were me personally, I'd run what's current, go w/ alky, a smaller pulley and retune. Run it till it dies and then go 402. IMO, It just doesn't make sense to me to put 6k in and get 50-100hp out.
Arnel
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From: http://www.mphparts.com 800-364-1975
You're making 500rwhp now, and want another 50-100rwhp and reliability... I would just go with a forged 346 and be done. It's less expensive, well proven, and given your modest power goals will get you there with ease.
Safety Car
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From: Hayward California
Originally Posted by Devildog5150
Thanks, I'm not spending the money to get 50-100hp, that's just a bonus, I really want the extra safety and peace of mind by going forged.
Of course if you're planning on selling it to offset than go for it.
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Le Mans Master
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From: Port Arthur, Texas 77642
Asking the same question myself. With your power goal of adding 50-100hp you can get it with 346, no problem. There are some CF members doing that now with stock bottom end, myself included. I am with you on the issue of safely making 600rwhp, my combo has 2500 miles on it but feel like I am living on borrowed time. At this point I am leaning toward a forged LS2 364ci. With FI I feel no need to go larger. I do however like the added strength of the LS2 block. Good Luck with Your Build! 
Scotty
Scotty
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Originally Posted by AVB
I know... I did what you are planning. It's just if I had it to do over, I would just have run the stocker for as long as it could take it. For some that I know, it would be for pretty good long time. A 402 would definitely be it's replacement.
Of course if you're planning on selling it to offset than go for it.
Of course if you're planning on selling it to offset than go for it.
402 I think is most cost effective/risk/reward ratio way to go. The labor counts for the majority of it.
Those of us that have had both, will tell you that we prefer the cubes. The big diference is in the availiable torque. Ironically GM has and is going down the same path even with their F/I SS for 2008.
Last edited by #001 2001 Z06; Oct 10, 2006 at 07:57 PM.
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From: http://www.mphparts.com 800-364-1975
I was going to run it until it blows on my Z06 too, but on a whim decided to test the waters and gauge interest on my LS6 long block. The motor was basically new (less than 9K miles), has never seen the track, and the only modification it ever saw was the addition of the ECS fuel system in preparation for my FI build. Other than that, the only thing it saw was the light of day in my garage.
I ended up getting enough cash to cover a very healthy chunk of my forged shortblock. Your mileage may vary, but for guys who have not yet modified their cars I would seriously consider taking the motor out while it's still fresh and perfectly healthy -- it will cost you less in the long run. I don't know too many people on here that run on the factory motor with FI for very long.
I ended up getting enough cash to cover a very healthy chunk of my forged shortblock. Your mileage may vary, but for guys who have not yet modified their cars I would seriously consider taking the motor out while it's still fresh and perfectly healthy -- it will cost you less in the long run. I don't know too many people on here that run on the factory motor with FI for very long.
Last edited by Tony @ MPH; Oct 10, 2006 at 03:35 PM.
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From: Elmhurst, IL (West Suburb of Chicago) & Home of MEGA Horsepower
St. Jude Donor '06
Originally Posted by peter pan
I can not answer your question on the 402, I am very happy with my little ole 346/7 that has run great for 4700 miles. Doug from ECS made a good point in another post, do not remember, that for 99% of the FI crowd the stock displacement is all you need. Give them a call or Andy at A&A, as I have an A&A DS1C that runs great and I decided to stay stock displacement as it meets my needs
Save the $2k for drivetrain parts and tires, as the forged 347 f/i motor will make more power than you will EVER USE on the street period!!:
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Instructor
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From: Lubbock Texas
Thanks alot it really is a tough choice, I was not thinking, I guess the LS2 would be a better choice as far as stock displacement goes, my block is a 98 and I have read some negative things about it so I will definately go with a new block over just rebuilding mine. I don't think anybody really addressed the question about whether I will be able to feel the difference in low end power that the stroker would provide since I have a 3000 stall, any thoughts?
Le Mans Master
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From: Port Arthur, Texas 77642
Originally Posted by Devildog5150
Thanks alot it really is a tough choice, I was not thinking, I guess the LS2 would be a better choice as far as stock displacement goes, my block is a 98 and I have read some negative things about it so I will definately go with a new block over just rebuilding mine. I don't think anybody really addressed the question about whether I will be able to feel the difference in low end power that the stroker would provide since I have a 3000 stall, any thoughts?
Scotty